Arion subfuscus group: Arion subfuscus

Family

Arionidae

Species

Arion subfuscus (Draparnaud, 1805)

Common name

Dusky arion

Description

The Arion subfuscus group typically contains slugs that are fairly large, often attaining a maximum length of 70 mm as fully mature adults. A. subfuscus and A. fuscus were treated as the same species (A. subfuscus) until recently. They can be separated by molecular techniques as well as by internal morphological characters explained below. They range in color from grey-brown to orange brown and usually have dark brown bands running down the sides, laterally. The pneumostomePneumostome:
This is the breathing hole on the right side of the mantle of molluscs. This allows air to pass through to the lung for gas exchange.(See also breathing pore).
is encircled by the stripe on the right side of the animal. Unlike others in this genus, individuals in the A. subfuscus group are rounded when contracted. The tuberclesTubercles:
An enlarged or raised region on the body of a slug. The shape of this structure is very variable. (See also tubercle)
are minute and elongated and the keelKeel:
Also known as the carina. This is a longitudinal ridge that runs dorsally along the apex of the tail of the animal.
is absent. The footFoot:
The muscular organ on the undersurface of the body of a mollusc upon which the animal rests or uses to crawl.
fringe has vertical bands running its length. The sole of this group is dirty-white, and the mucus produced may either be yellow, orange and on rare occassions clear. Molecular techniques can also be used to identify members of this group.

The distinguishing morphological features of each species are:

Arion subfuscus (Draparnaud, 1805) - GenitaliaGenitalia:
The reproductive structures of an animal. May refer to either male or female structure.
large, light lavender in color and located on the margin of the digestive gland

Arion fuscus (Muller, 1774) - GenitaliaGenitalia:
The reproductive structures of an animal. May refer to either male or female structure.
small, dark in color and completely embedded in the digestive gland.

Native range

Northern and Western Europe

Distribution

North America:

• U.S.: California, Connecticut, Delaware, Kentucky, Maine, Maryland, Massachusetts, New Hampshire, New York, North Carolina, Pennsylvania, Rhode Island, Vermont, Virginia, Washington D.C., Wisconsin
• Canada

Europe

Ecology

This pestifierous species can be found in a variety of habitats (e.g. forests, fields, gardens). It has been suggested that Arion subfuscus may be a very competitive species as it has been documented that in some areas where the slugSlug:
A snail that either does not possess a shell or has one that is very reduced (no definite coiling) or internal.
has been introduced, it occurs in numbers larger than that of native species.

Synonyms

• Limax subfuscus Draparnaud, 1805
• Arion krynickii Kaleniczenko, 1851
• Arion brunneus Lehmann, 1862
• Arion esthonicus Poska-Teiss, 1927

References

Anderson 2005; Beyer and Saari 1978; Grimm et al. 2009; Kantor et al. 2009; McDonnell, R.J. et al. 2011; Pinceel et al. 2005; Roth and Sadeghian 2006